Objective To observe the effect of electroacupuncture(EA) of “Weizhong”(BL40) on the disorder of iron metabolism and the level of oxidative stress after lumbar multifidus muscle injury(LMMI)

so as to explore its mechanisms underlying promoting the repair of LMMI. Methods Male SD rats were randomly divided into normal

model and EA groups(6 rats in each group). The LMMI model was established by injecting 0.5% bupivacaine(BPVC) solution(400 μL) into the lumbar multifidus muscle with the syringe-needle close to the spinous process(L4-L5). Twenty-four hours after successful establishment of the model

EA(2 Hz/15 Hz

2 mA) was applied to bilateral BL40 for 30 min

once a day for 2 days. Histopathological changes of the multifid muscle were observed under microscope after H.E. staining

and the iron granules in the multifid muscle tissue observed after Prussian blue staining. The expression of glutathione synthase(GSS) was detected by Western blot

and the expressions of iron regulatory protein 1(IRP1)

ferroportin(Fpn)

ferritin heavy chain 1(FTH1

iron metabolism-related proteins) and gluta-thione peroxidase 4(GPX4

functions in protecting cells against detrimental lipid peroxidation and governing a novel form of regulated necrotic cell death

called ferroptosis) mRNAs were detected by quantitative real-time PCR. The contents of glutathione(GSH) and malondialdehyde(MDA) were measured by biochemical methods. Results H.E. staining showed large areas of necrosis and breakage of muscle fibers

disordered arrangement of muscle fibers

widened muscle cell space

accompanying with a large number of inflammatory cell infiltration in the multifidus muscle tissue of the model group

which was relatively milder in the EA group. Outcomes of Prussian blue staining showed that compared with the normal group

there were more iron particles in the multifidus muscle tissue and enlarged muscle fiber gaps

which was also milder in the EA group. Compared with the normal group

the expression level of IRP1 mRNA and content of MDA were significantly increased(P<0.001)

the expression levels of Fpn

FTH1 and GPX4 mRNAs and GSS protein

and the content of GSH were considerably decreased(P<0.001) in the model group. In comparison with the model group

the increase of IRP1 mRNA expression and MDA content

as well as the decrease of Fpn

FTH1 and GPX4 mRNAs expressions and GSH content were reversed in the EA group(P<0.001

P<0.05

P<0.01). Conclusion EA of BL40 has a protect effect in BPVC-induced injury of lumbar multifidus muscle in rats

which may be related to its functions in improving iron metabolism to reduce oxidative damage by regulating expression of IRP1

Fpn and FTH1.